A thin film transistor (TFT) adopts an amorphous silicon (a-Si) material for an active layer, but the carrier mobility of the a-Si material is only 0.5 cm2/V·s, which is difficult to meet the requirement of a large-sized display apparatus in term of driving frequency. The carrier mobility of a poly-silicon (p-Si) material is obviously higher than that of the a-Si material, but a temperature of a p-Si preparation process is generally higher than 600° C., so the p-Si material is unsuitable for common glass adopted by most display apparatuses. Therefore, those skilled in the art develop a manufacturing process of a new generation of TFT for preparing a Low Temperature Poly Silicon (LTPS) active layer.
The temperature of the preparation process of the LTPS is lower than 600° C., the LTPS can be suitable for the common glass, and generally, excimer laser with a certain energy is utilized to carry out laser radiation on a-Si in a mode of performing laser crystallization by adopting Excimer Laser Annealing (ELA) so as to crystallize the a-Si into p-Si.